The 904L has more Nickel and Chromium in the alloy. Hence improved corrosion and pitting resistance. Nothing particularly exotic about it, it's a standard commercial grade of SS.
An answer frm the ROLEX FAQ frm other forum ........................... What type of Stainless Steel does Rolex use? Most watch manufacturers use stainless steel 1.4435 or 316L. Rolex uses stainless steel 1.4439 or 904L which is slightly different from 1....
The 316L Stainless steel is far less scratch resistant than the 904L because it has a much higher Rockwell hardness. The 316L has less nickel in it and is far brighter in appearance and tends to stay that way. Nickel can be an irratant to some. The 904L i...
that has been doing watches for over half a century that the old steel pitted with age and the new has resistance against pitting.. or so he thinks as he has yet to see a piece with the 904L with pitting.. it was a brief conversation we had so i hope im r...